HADOOP-13414. Hide Jetty Server version header in HTTP responses. Contributed by Surendra Singth Lilhore.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/http/HttpServer2.java

@@ -431,6 +431,7 @@ public final class HttpServer2 implements FilterContainer {
       HttpConfiguration httpConfig = new HttpConfiguration();
       httpConfig.setRequestHeaderSize(requestHeaderSize);
       httpConfig.setResponseHeaderSize(responseHeaderSize);
+      httpConfig.setSendServerVersion(false);
 
       for (URI ep : endpoints) {
         final ServerConnector connector;